The present invention relates to an optical connector for two-way optical communications. In particular, it relates to an optical connector that comprises a light-emitting element, a light-receiving element, and sleeves that optically connect the light-emitting element and the light-receiving element to optical fibers of an optical plug.
As an example, FIGS. 1A and 1B show a conventional optical connector for two-way optical communications described in Japanese Patent Application Laid Open No. 2000-304980 (issued on Nov. 2, 2000, referred to as literature 1 hereinafter). FIG. 1A shows an optical connector (receptacle) on an apparatus, and FIG. 1B shows an optical plug to be fitted to the optical connector.
A housing 11 of an optical connector 10 has a pair of storage sections 12, each of which houses either of a light-emitting element module (a transmission module) 13 and a light-receiving element module (a reception module) 14. In front of each of the storage sections 12, a receiving tube 15 extending frontward is provided, and a sleeve 16 is fitted into each receiving tube 15. In FIG. 1A, reference numeral 17 denotes a cap fitted on the rear of the optical connector 10, and reference numeral 18 denotes back sheets supporting the light-emitting element module 13 and the light-receiving element module 14.
On the other hand, as shown in FIG. 1B, an optical plug 20 comprises a pair of optical fibers 22 each having a ferrule 21 attached to the front end thereof, a housing 24 having tubular walls 23 each housing and protecting one ferrule 21, a spring cap 25 fitted onto and fixed to the housing 24, and a boot 26 fitted to the rear of the spring cap 25. In FIG. 1B, reference numeral 27 denotes springs that bias the ferrules 21 frontward.
When the optical plug 20 structured as described above is fitted into the optical connector 10 structured as described above, the paired ferrules 21 each holding one optical fiber 22 are inserted into the corresponding receiving tubes 15, and the front surface of each ferrule 21, at which the end face of the optical fiber 22 is exposed, faces the front surface of the sleeve 16 fitted in the receiving tube 15 with a small gap therebetween. Thus, the optical fibers 22 are optically connected to the light-emitting element module 13 and the light-receiving element module 14 via the sleeves 16. Here, the sleeves 16 are composed of a light-propagating optical fiber 16a housed and fixed in a cylindrical holder 16b. 
As described above, according to the prior art, the sleeves are each composed of the light-propagating waveguide (optical fiber) housed in the cylindrical holder and inserted into the receiving tube in the housing of the optical connector. For insertion, the sleeves are press-fitted into the receiving tubes for positioning and securing. Thus, a problem may arise that a stress is caused by the pressing and exerted on the waveguides, thereby compromising the optical property of the waveguides.
Besides, in the literature 1 described above, there are described a sleeve composed of a waveguide having an integral guide section at one end, and a sleeve unit composed of a transmission sleeve with such a guide section and a reception sleeve with such a guide section which are connected via a link section. In any case, the guide section surrounding the waveguide is press-fitted and secured in a receiving tube, and thus, there is a possibility that a stress caused by the press fitting affects the optical function of the waveguide, as in the case described above.